'67 GTO ignition switch and key cylinder mating
 

The original ignition switch on my '67 GTO gave up the ghost. I bought an OEM replacement switch. The key cylinder was removed from the original switch prior to disconnecting it. (pic below) Problem is, I can't get the key cylinder to seat properly in the OEM replacement. The process for removing the key cylinder from the original switch involves turning the ignition switch to the accessory position (to the left) then inserting a small pick or paper clip into the release hole on the cylinder and the cylinder will release. Then the dash bezel can be removed, the key cylinder removed and the switch replaced. Replacement of the switch and key cylinder SHOULD be pretty much straight forward, but I've had no success getting the key cylinder to fully seat in the switch. Has anyone here done this successfully?

I finally got it. The new OEM switch had a slight tolerance mismatch with the original key cylinder. I filed the cylinder tabs slightly and it dropped in. Yea a win!